XML Navigation

Question

I am trying to navigate through an xml document which i have called from an RSS Feed link.

Below are the extract codes:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim doc As New System.Xml.XmlDocument
        doc.Load("http://earthquake.usgs.gov/earthquakes/shakemap/rss.xml")

        Dim list = doc.GetElementsByTagName("item")
        Dim i As Integer = 0
        For Each item As System.Xml.XmlElement In list
            Label1.Text = (doc.GetElementsByTagName("title").Item(i).InnerText)
            Label2.Text = (doc.GetElementsByTagName("description").Item(i).InnerText)
            Label3.Text = (doc.GetElementsByTagName("link").Item(i).InnerText)
            Label4.Text = (doc.GetElementsByTagName("pubDate").Item(i).InnerText)
            Label5.Text = (doc.GetElementsByTagName("geo:lat").Item(i).InnerText)
            Label6.Text = (doc.GetElementsByTagName("geo:long").Item(i).InnerText)
            Label7.Text = (doc.GetElementsByTagName("dc:subject").Item(i).InnerText)
            Label8.Text = (doc.GetElementsByTagName("eq:seconds").Item(i).InnerText)
            Label9.Text = (doc.GetElementsByTagName("eq:depth").Item(i).InnerText)
            Label10.Text = (doc.GetElementsByTagName("eq:region").Item(i).InnerText)
            i = i + 1
        Next
    End Sub

However, I wish to navigate through the xml document by adding a previous, next, first and last buttons. Any ideas would be helpful

Answer 1

You've asked this in a forum which doesn't really deal with ASP.NET (see http://forums.asp.net for that), but if I show you a way with a Windows forms program hopefully you can convert it ASP.NET by saving the currIndex and shakes variables in session variables. And implement the first and last buttons yourself.

Public Class Form1

	Dim shakes As New List(Of Shaken)
	Dim currIndex As Integer = 0

	Class Shaken
		Property Title As String
		Property Description As String
		Property Link As Uri
		Property PubDate As DateTime
		Property Latitude As Double
		Property Longitude As Double
		Property Subject As String
		Property Duration As Double
		Property Depth As Double
		Property Region As String
	End Class

	Sub GetData()
		shakes.Clear()
		' chances are the data are in US format
		Dim locale = Globalization.CultureInfo.CreateSpecificCulture("en-US")

		Dim doc As New System.Xml.XmlDocument
		doc.Load("http://earthquake.usgs.gov/earthquakes/shakemap/rss.xml")

		Dim list = doc.GetElementsByTagName("item")
		Dim i As Integer = 0
		For Each item As System.Xml.XmlElement In list

			shakes.Add(New Shaken With {
			.Title = doc.GetElementsByTagName("title").Item(i).InnerText,
			.Description = doc.GetElementsByTagName("description").Item(i).InnerText,
			.Link = New Uri(doc.GetElementsByTagName("link").Item(i).InnerText),
			.PubDate = DateTime.Parse(doc.GetElementsByTagName("pubDate").Item(i).InnerText, locale),
			.Latitude = CDbl(doc.GetElementsByTagName("geo:lat").Item(i).InnerText),
			.Longitude = CDbl(doc.GetElementsByTagName("geo:long").Item(i).InnerText),
			.Subject = doc.GetElementsByTagName("dc:subject").Item(i).InnerText,
			.Duration = CDbl(doc.GetElementsByTagName("eq:seconds").Item(i).InnerText),
			.Depth = CDbl(doc.GetElementsByTagName("eq:depth").Item(i).InnerText),
			.Region = doc.GetElementsByTagName("eq:region").Item(i).InnerText
			})

			i += 1

		Next

		' order them by PubDate for neatness
		shakes = shakes.OrderBy(Function(s) s.PubDate).ToList

	End Sub

	Sub ShowDatum(n As Integer)
		lblTitle.Text = shakes(n).Title
		lblDescription.Text = shakes(n).Description
		lblLink.Text = shakes(n).Link.ToString
		lblPubDate.Text = shakes(n).PubDate.ToString("yyyy-MM-dd")
		lblLatitude.Text = shakes(n).Latitude.ToString
		lblLongitude.Text = shakes(n).Longitude.ToString
		lblSubject.Text = shakes(n).Subject
		lblDuration.Text = shakes(n).Duration.ToString
		lblDepth.Text = shakes(n).Depth.ToString
		lblRegion.Text = shakes(n).Region

	End Sub

	Private Sub bnPrevious_Click(sender As Object, e As EventArgs) Handles bnPrevious.Click
		If currIndex > 0 Then
			currIndex -= 1
			ShowDatum(currIndex)
			If currIndex = 0 Then
				bnPrevious.Enabled = False
			End If
			lblCounter.Text = String.Format("{0} of {1}", currIndex + 1, shakes.Count)
		End If
		bnNext.Enabled = True

	End Sub

	Private Sub bnNext_Click(sender As Object, e As EventArgs) Handles bnNext.Click
		If currIndex < shakes.Count - 1 Then
			currIndex += 1
			ShowDatum(currIndex)
			If currIndex = shakes.Count - 1 Then
				bnNext.Enabled = False
			End If
			lblCounter.Text = String.Format("{0} of {1}", currIndex + 1, shakes.Count)

		End If
		bnPrevious.Enabled = True

	End Sub

	Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
		GetData()
		currIndex = 0
		bnPrevious.Enabled = False
		lblCounter.Text = String.Format("{0} of {1}", currIndex + 1, shakes.Count)
		ShowDatum(currIndex)

	End Sub

End Class

I gave the labels more descriptive terms, and added a label for the current value of the counter.

HTH,

Andrew

Answer 2

Oh yeah, forgot to mention: the description field doesn't seem to be right. But whatever it is appears to have a URL for an image which you might want to put on the page too.

--
Andrew

Answer 3

Thanks Andrew, I'm new to this that's why got in the wrong forum.

Thanks Mate.